Laminated glass

ABSTRACT

A laminated glass with a good appearance and heat shielding properties which comprises glass sheets 11a and 11b characterized by a UV transmittance as stipulated in ISO-9050 of at most 30%, a visible light transmittance of at least 70% under a standard light source A, a dominant wavelength of from 480 to 570 nm and an excitation purity of at most 6% at the actual thickness and an interlayer 12 interposed between the glass sheets, wherein the interlayer has heat shielding fine particles with particle diameters of at most 0.2 mum dispersed therein.

TECHNICAL FIELD

The present invention relates to laminated glass having heat shieldingproperties (hereinafter referred to as IR cutoff properties).

BACKGROUND ART

Vehicles mount heat shielding windowpanes in order to intercept incidentsolar energy into the compartment and decrease the temperature rise inthe compartment and the load on the air conditioner. As heat shieldingwindowpanes, thin film-deposited glass sheets having thin films ofvarious metals and metal oxides layered on the glass surfaces may bementioned. Because of the electrical conductivity of films of thesevarious metals and metal oxides, thin film-deposited glass sheetsintercept radio waves.

On the other hand, as windowpanes for vehicles, especially forautomobiles, glass sheets having the functions of radio, TV and GPSantennas are often used. Automobiles equipped with various functionalsystems (such as the electric road pricing system and the keyless entrysystem) including sensors installed inside them to send out or receiveradio waves are also proposed. In order to secure the normal function asan antenna and normal operations of various systems, windowpanes have totransmit radio waves.

Therefore, thin film-deposited glass sheets need special tuning tosecure the function as an antenna. Further, thin film-deposited glasssheets can hardly be used directly for systems that require transmissionof electric waves for radio communication between inside and outsidevehicles.

From this viewpoint, a laminated glass that transmits radio waves aswell as intercepts heat radiation is disclosed in JP-A-8-259279. Thelaminated glass disclosed therein uses an interlayer in which functionalfine particles with particle diameters of at most 0.2 μm are dispersed.The laminated glass is supposed to not only intercept heat radiation butalso suppress radio interference.

However, this laminated glass has an unfavorable appearance due to thefunctional fine particles dispersed in the interlayer. In other words,incorporation of as many fine particles as necessary for satisfactory IRcutoff properties for windowpanes of automobiles results in aninterlayer having a high haze and hence a laminated glass having a highhaze.

The object of the present invention is to provide a laminated glass witha less unfavorable appearance and IR cutoff properties which has notbeen known so far in order to solve the above-mentioned problems of theprior art.

DISCLOSURE OF THE INVENTION

The present invention has been accomplished to solve the above-mentionedproblems and provides a laminated glass comprising plural glass sheetsand an interlayer interposed between the plural glass sheets, whereinthe interlayer has heat shielding fine particles with particle diametersof at most 0.2 μm dispersed therein, and at least one of the pluralglass sheets is characterized by a UV transmittance as stipulated inISO-9050 of at most 30%, a visible light transmittance of at least 70%under a standard light source A, a dominant wavelength of from 480 to570 nm and an excitation purity of at most 6% at the actual thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of one embodiment of the laminatedglass of the present invention.

FIG. 2 is a graph showing the spectral transmittances of laminatedglasses.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be described in further detail byreferring to Drawings. FIG. 1 is a schematic sectional view of oneembodiment of the laminated glass of the present invention. Thelaminated glass 1 is a laminate comprising two glass sheets 11 a and 11b and an interlayer 2 interposed therebetween.

The interlayer 2 is a polyvinylbutyral film or a ethylene-vinyl acetatecopolymer film commonly used as the interlayer of a laminated glass. Inthe interlayer 2, heat shielding fine particles (hereinafter referred toas IR cutoff fine particles) with particle diameters of at most 0.2 μmare dispersed. It is preferred to disperse IR cutoff fine particles withparticle diameters of from 0.15 to 0.001 μm.

The IR cutoff fine particles may be, for example, fine particles made ofa metal, an oxide, a nitride or a sulfide of Sn, Ti, Si, Zn, Zr, Fe, Al,Cr, Co, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V or Mo which may be doped withSb or F, and may be made of a single species or more than one species.It is helpful to use a single species or more than one species ofparticles mixed or coated with an organic resin to attain variousproperties necessary for use in automobiles.

It is preferred to use fine particles of at least one of tin oxide dopedwith antimony (ATO) and indium oxide doped with tin (ITO) as the IRcutoff fine particles because the excellent IR cutoff properties of ATOfine particles and ITO particles makes it possible to reduce the amountof the IR cutoff fine particles in the interlayer. ITO fine particlesare even more excellent than ATO fine particles in IR cutoff properties.Therefore, a smaller amount of ITO particles are required than ATOparticles to obtain desired IR cutoff properties. Therefore, ITO fineparticles are particularly preferable for use as the IR cutoffparticles.

On the other hand, it is necessary to disperse a certain amount of IRcutoff particles in the interlayer in order to obtain desired IR cutoffproperties whether the IR cutoff particles are ATO or ITO fine particlesor other fine particles. Therefore, it is difficult to keep the haze ofthe interlayer low under conditions which guarantee desired IR cutoffproperties and radio wave transmittance.

For this reason, glass sheets having the following properties are usedas both the glass sheets 11 a and 11 b shown in the figure are. Glasssheets characterized by a UV transmittance as stipulated in ISO-9050 ofat most 30%, a visible light transmittance of at least 70% under astandard light source A, a dominant wavelength of from 480 to 570 nm andan excitation purity of at most 6% at the actual thickness.

For the glass sheets having the above-mentioned characteristics, sodalime silica glass substantially having the following composition interms of mass percentage is preferably used.

SiO₂: 65-75%, Al₂O₃: 0.1-5%, Na₂O+K₂O: 10-18%, CaO: 5-15%, MgO: 1-6%,SO₃: 0.05-2%, total iron expressed as Fe₂O₃: 0.3-1%, total ceriumexpressed as CeO₂ or/and TiO₂: 0.5-2%.

Glass sheets having the above-mentioned characteristics, especiallyglass sheets having the above-mentioned composition, have heat absorbingproperties, and therefore can impart a certain degree of IR cutoffproperties attributable to their own IR cutoff properties to thelaminated glass. Hence, the laminated glass can have satisfactory IRcutoff properties as a whole even with less amount of IR cutoff fineparticles. Consequently, it is possible to lower the haze of theinterlayer and improve the appearance of the laminated glass.

Thus, use of glass sheets having IR cutoff properties can reduce theamount of the IR cutoff fine particles in the interlayer. Specificallyspeaking, because ITO fine particles are preferable as IR cutoffparticles as mentioned above, the amount of the ITO fine particlesdispersed in the interlayer is preferably as follows: from 0.1 to 0.5part by mass in relation to 100 parts by mass of the entire interlayer.Thus, it is possible to keep the haze of the laminated glass at most 1%and impart satisfactory overall IR cutoff properties to the laminatedglass.

In addition, use of glass sheets characterized by a UV transmittance asstipulated in ISO-9050 of at most 15%, a visible light transmittance ofat least 70% under a standard light source A, a dominant wavelength offrom 480 to 570 nm and an excitation purity of at most 6% as stipulatedby ISO-9050 at the actual thickness produces the following effects.Namely, use of the above-mentioned glass sheets makes it possible toprovide a laminated glass having UV shielding properties while loweringthe haze attributable to the IR cutoff particles. Therefore, thelaminated glass of the present invention using the above-mentioned glasssheets can attain both the functional properties, IR cutoff propertiesand shielding properties.

In the present invention, the UV transmittance of a glass sheet isexpressed as that measured at the actual thickness of the glass sheet.The glass sheets in the present invention are characterized in that theUV transmittance as stipulated in ISO-9050 is at most 30%, preferably atmost 15%, at the actual thickness.

In the present invention, the visible light transmittance of a glasssheet is expressed as that measured under a standard light source A atthe actual thickness of the glass sheet. The glass sheets in the presentinvention are characterized in that the visible light transmittancemeasured in accordance with the visible light transmittance teststipulated in JIS R3212-1992 is at least 70%.

The glass sheets in the present invention are characterized in that thedominant wavelength measured in accordance with the method of measuringa dominant wavelength stipulated in JIS Z8701-1982 is from 480 to 570nm, preferably from 500 to 540 nm.

In the present invention, the excitation purity of a glass sheet isexpressed as that measured at the actual thickness. The glass sheets inthe present invention are characterized in that the excitation puritymeasured in accordance of the method of measuring an excitation puritystipulated in JIS Z8701-1982 under a standard light source A is at most6%, preferably from 2 to 6%.

In the present invention, the thickness of each glass sheet ispreferably from 1.2 to 5 mm. The thickness of the plural glass sheetsmay be the same or different. When the plural glass sheets have the samethickness, the thickness is preferably from 1.7 to 3 mm. When the pluralglass sheets have different thickness, it is preferred that the thinnerglass sheet has a thickness of from 1.2 to 2.5 mm, and the thicker onehas a thickness of from 2 to 3 mm.

In the illustrated embodiment, the laminated glass comprises two glasssheets and an interlayer interposed between them. The laminated glass ofthe present invention may comprise more than two glass sheets andinterlayers interposed therebetween. In this case, at least one of theplural interlayers should be an interlayer having IR cutoff fineparticles dispersed therein.

The laminated glass of the present invention is characterized in that atleast one of the glass sheets is characterized by a UV transmittance asstipulated in ISO-9050 of at most 30%, a visible light transmittance ofat least 70% under a standard light source A, a dominant wavelength offrom 480 to 570 nm and an excitation purity of at most 6% at the actualthickness. In the above-mentioned embodiment, the two glass sheets bothhave the above-mentioned characteristics. In the case of a laminatedglass comprising two glass sheets like the illustrated embodiment, it ispreferred that both the glass sheets have the above-mentionedcharacteristics in view of the matching of the glass sheets in shape.

The laminated glass of the present invention is suitable for windowpanesof automobiles. As windowpanes of automobiles, glass sheets having thefunctions of radio, TV and CPS antennas are often used. Besides, mostautomobiles these days are equipped with various functional systems suchas the electric road pricing system and the keyless entry system whichsend out or receive radio waves through windowpanes. Therefore, glasssheets which transmit radio waves are required as windowpanes forautomobiles.

The laminated glass of the present invention has IR cutoff propertieseven without using a glass sheet having a thin metal or metal oxidefilm. Because the sheet resistance of the laminated glass, especially ofthe glass sheets, is large for this reason, the laminated glass cantransmit radio wave transmission. Therefore, the laminated glass of thepresent invention is suitable for windowpanes of automobiles. The sheetresistances of the glass sheets in the present invention are preferablyat least 20 kΩ/□, in particular at least 10 MΩ/□.

The interlayer in the present invention is obtainable by the methoddescribed below. Firstly, IR cutoff fine particles having particlediameters less than 0.2 μm are dispersed in a plasticizer used for theinterlayer. Then, the plasticizer having the IR cutoff fine particlesdispersed therein is added to a resin solution for the interlayer andkneaded to obtain a raw resin for film. Then, the raw resin is molded,for example, by extrusion into film to obtain an interlayer having IRcutoff fine particles dispersed therein.

At the time of addition of the plasticizer, various additives may beadded to the resin solution for the interlayer. As the additives,various pigments, organic UV absorbers and organic heat absorbers may bementioned. As the plasticizer and the solvent in the resin solution forthe interlayer, already known ones may be used.

Now, specific Examples of the present invention will be explained.

LAYER EXAMPLE 1

10 g of 3GH (triethylene glycol-di-2-ethyl butyrate) containing ITO fineparticles (particle diameters of at most 0.02 μm) dispersed therein (theamount of the ITO fine particles was 1 g), 130 g of ordinary 3GH and 360g of PVB (polyvinylbutyral) resin were obtained. The 3GH was added tothe PVB resin and kneading and mixing was done with a three-roll mixerat about 70° C for about 15 minutes. The resulting raw resin for filmwas molded at about 190° C with an extruder into film having a thicknessof about 0.8 mm and wound up on a roll to obtain an interlayerdesignated as Layer Example 1.

LAYER EXAMPLE 2

The same procedure as in Layer Example 1 was followed except that theamount of the ITO fine particles in 10 g of the 3GH (triethyleneglycol-di-2-ethyl butyrate) containing ITO fine particles (particlediameters of at most 0.02 μm) dispersed therein was changed from 1 g to2.5 g to obtain an interlayer designated as Layer Example 2.

GLASS EXAMPLES

Three kinds of glass sheets of 1000×1500 (mm) in size and 2 mm inthickness were obtained. The three kinds of glass sheets are as follows.

GLASS EXAMPLE 1

Glass sheets made of ordinary colorless soda lime silica glass.

GLASS EXAMPLE 2

Glass sheets made of green soda lime silica glass.

GLASS EXAMPLE 3

Soda lime silica glass substantially having the following composition interms of mass percentage which is favorable as sheet glass characterizedby a UV transmittance as stipulated in ISO-9050 of at most 30%, avisible light transmittance of at least 70% under a standard lightsource A, a dominant wavelength of from 480 to 570 nm and an excitationpurity of at most 6% at 2.00 mm thickness.

SiO₂: 71%, Al₂O₃: 1.7%, Na₂O+K₂O: 12.8%, CaO: 8%, MgO: 3.5%, SO₃: 0,2%,total iron expressed as Fe₂O₃: 0.62%, total cerium expressed as CeO₂:1.55%, TiO₂: 0.35%.

Then, each two glass sheets selected from Glass Examples 1 to 3 werebonded by using an interlayer designated as Layer Example 1 or 2 toobtain laminated glasses having the following structures (LaminateExamples 1 to 6).

LAMINATE EXAMPLE 1

Glass Example 3/Layer Example 1/Glass Example 1

LAMINATE EXAMPLE 2

Glass Example 3/Layer Example 1/Glass Example 2

LAMINATE EXAMPLE 3

Glass Example 1/Layer Example 1/Glass Example 1

LAMINATE EXAMPLE 4

Glass Example 3/Layer Example 2/Glass Example 1

LAMINATE EXAMPLE 5

Glass Example 3/Layer Example 2/Glass Example 2

LAMINATE EXAMPLE 6

Glass Example 1/Layer Example 2/Glass Example 1

The transmittances at wavelengths between 300 and 2100 nm of theresulting laminated glasses designated as Laminate Examples 1 to 6 weremeasured to obtain the visible light transmittances T_(v) (%) and thesolar transmittances T_(e) (%) as stipulated in JIS R3106. The hazes (%)of the laminated glasses were measured in accordance with JIS K6714.

The results are shown in the following table and FIG. 2 showing spectraltransmittances of laminated glasses, Laminate Examples 1 to 3; FIG.2(a), Laminate Examples 4 to 6; FIG. 2(b), the ordinate; transmittance(%), the abscissa; wavelength (nm)).

Laminate Example T_(v) T_(e) Haze 1 77.9 47.8 0.3 2 73.2 41.0 0.3 3 87.567.4 0.2 4 75.7 43.9 0.5 5 71.0 37.8 0.6 6 84.9 60.0 0.4

The results in the above table indicate that the use glass sheets ofGlass Example 3 (in Laminate Examples (1, 2, 4 and 5) made it possibleto obtain laminated having desired IR cutoff properties with smallamounts of ITO fine particles. The IR cutoff properties are expressed asthe solar transmittance T_(e) Laminate Examples 1, 2, 4 and 5 in whichglass sheets and interlayers were so selected that the T_(e) would befrom 30 to 50% are favorable examples of the laminated glass of thepresent invention.

INDUSTRIAL APPLICABILITY

According to the present invention, by the use of the interlayercontaining IR cutoff fine particles with particle diameters of at most 2μm dispersed therein, it is possible to a laminated glass having IRcutoff properties. The use of glass sheets characterized by a UVtransmittance as stipulated in ISO-9050 of at most 30%, a visible lighttransmittance of at least 70% under a standard light source A, adominant wavelength of from 480 to 570 nm and an excitation purity of atmost 6% at the actual thickness to prevent an unfavorable appearanceresulting from the IR cutoff fine particles dispersed therein makes itpossible to provide a laminated glass having IR cutoff properties withno unfavorable sacrifice of the appearance.

Further, by virtue of the use of such glass sheets as described above,it is possible to obtain a laminated glass having both IR cutoffproperties and UV shielding properties easily.

What is claimed is:
 1. A laminated glass comprising plural glass sheetsand an interlayer interposed between the plural glass sheets, whereinthe interlayer has heat shielding fine particles with particle diametersof at most 0.2 μm dispersed therein, and at least one of the pluralglass sheets is characterized by a UV transmittance as stipulated inISO-9050 of at most 30%, a visible light transmittance of at least 70%under a standard light source A, a dominant wavelength of from 480 to570 nm and an excitation purity of at most 6% at 2.00 mm thickness, andwherein said laminated glass has a haze of at most 1.0% in accordancewith JIS K6714, a solar transmittance T_(e) of from 30 to 50% asstipulated in JIS R3106, and a visible light transmittance T_(v) of atleast 71%.
 2. The laminated glass according to claim 1, wherein theinterlayer is a polyvinylbutyral film.
 3. The laminated glass accordingto claim 1, wherein the heat shielding fine particles have particlediameters of from 0.001 to 0.15 μm.
 4. The laminated glass according toclaim 1, wherein the heat shielding fine particles contain fineparticles made of a metal, an oxide, a nitride or a sulfide of Sn, Ti,Si, Zn, Zr, Fe, Al, Cr, Co, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V or Mo whichmay be doped with Sb or F.
 5. The laminated glass according to claim 1,wherein the heat shielding fine particles are fine particles of tinoxide doped with antimony.
 6. The laminated glass according to claim 1,wherein the heat shielding fine particles are fine particles of indiumoxide doped with tin.
 7. The laminated glass according to claim 6,wherein the amount of the particles of indium oxide doped with tindispersed in the interlayer is from 0.1 to 0.5 parts by weight inrelation to 100 parts by weight of the entire interlayer.
 8. Thelaminated glass according to claim 1, which is a windowpane forautomobiles.
 9. The laminated glass according to claim 1, wherein saidat least one of the plural glass sheets has the following composition interms of mass percentage: SiO₂: 65-75%, Al₂O₃: 0.1-5%, Na₂O+K₂O: 10-18%,CaO: 5-15%, MgO: 1-6%, SO₃: 0.05-2%, total iron expressed as Fe₂O₃:0.3-1%, total cerium expressed as CeO₂ and/or TiO₂: 0.5-2%.
 10. Thelaminated glass according to claim 9, wherein each glass sheet has athickness of from 1.2 to 5 mm.
 11. The laminated glass according toclaim 10, wherein each glass sheet has a thickness of from 1.7 to 3 mm.12. The laminated glass according to claim 9, wherein the plural glasssheets have different thicknesses, one of from 1.2 to 2.5 mm and anotherone of from 2 to 3 mm.
 13. The laminated glass according to claim 1,wherein each glass sheet has a thickness of from 1.2 to 5 mm.
 14. Thelaminated glass according to claim 13, wherein each glass sheet has athickness of from 1.7 to 3 mm.
 15. The laminated glass according toclaim 1, wherein the UV transmittance as stipulated in ISO-9050 is atmost 15%.
 16. The laminated glass according to claim 1, wherein theplural glass sheets have different thicknesses, one of from 1.2 to 2.5mm and another one of from 2 to 3 mm.
 17. The laminated glass accordingto claim 1, which has a haze of at most 0.3% in accordance with JISK6714.